1. Field of the Invention
The invention disclosed in this specification relates to a semiconductor device utilizing a semiconductor element and a manufacturing method thereof.
2. Description of the Related Art
Attention has been focused on a technique of using a semiconductor thin film formed over a substrate having an insulating surface to form a transistor. The transistor is applied to a wide range of electronic devices such as an integrated circuit (IC) or an image display device (display device). Further, a technique of using an oxide semiconductor for a semiconductor thin film that can be used for a transistor has been attracting attention.
For example, it has been confirmed that an oxide semiconductor containing an In—Ga—Zn-based oxide is applicable to a channel formation region of a thin film transistor (Patent Document 1).